Ultrasonic bonding has been accomplished at various frequency up to about 125 KHz. These bonds have principally been made between gold bond wires and aluminum or aluminum alloy surfaces on integrated circuits. Interconnections have been made between aluminum wires and aluminum surfaces, but these interconnections have been made at a frequency of about 60 KHZ. Such interconnections are described in the paper entitled EFFECT OF ULTRASONIC VIBRATION ON WIRE BONDING, by Hiroshi Haji, Toshiaki Morita, Hideharu Nakashima and Hideo Yoshinaga, Department of Materials Science and Technology, graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, Japan. The aluminum to aluminum interconnections made at this lower frequency has not produced a sufficient metal interchange between the bond wire and the bond surface to produce a strong bond. Hence a process is needed to achieve, through metal interchange, a strong bond wire to bond surface connection at lower temperatures and shorter bonding times.
Bonds have been made at 120 KHz as described in an article in the ICEMM Proceedings of 1993, HIGH RELIABILITY WIRE BONDING TECHNOLOGY BY THE 120 KHZ FREQUENCY OF ULTRASONIC, by Yuji Shirai, Kanji Otsuka, Takashi Araki, Isao Seki, Kouiti Kikuchi, Nobuhire Fujita, and Takashi Miwa. This article shows a reduced wire bond failure rate at 120 KHz, and discusses gold wedge bonding at room temperature.